This invention relates to treatment of water-containing plastic and production of oriented polymer film therefrom. In particular, it relates to polyacrylonitrile (PAN) compositions and methods for applying a glycol plasticizer to water-containing substrates during film manufacture.
High nitrile polymers are employed in making packaging films, foils and sheets having good resistance to passage of oxygen and water vapor. PAN homopolymer film is an excellent gas barrier material; however, it lacks adequate flex-crack resistance in unmodified form, even after molecular orientation. Addition of an inert or non-hazardous plasticizer to improve flex performance, stress-stain properties, impact strength, etc. is desirable for food packaging or wrap film.
Prior art film manufacturing techniques may incorporate plasticizers or other compatible impregnants prior to the formation and orientation of films. It is an object of the invention to provide a simplified system for treating water-containing sheets with organic impregnants, such as glycol plasticizers.